Archive for the ‘Manifolds’ Category

Radiant floor heat uses a closed system with loop connections that circle back to the unit. These connections are made by putting threaded adapters on the ports and looping the tubing back to the unit. Hot water is pumped through the tubing, evenly warming the room and saving energy by heating a solid block of concrete that will retain the heat.

Each loop is connected securely to a manifold and when the system turns on, hot water is pumped through the tubing.  The water heats the concrete slab and the heat rises from the floors into the rest of the room.  When the room reaches the temperature set by your thermostat, the hot water will stop circulating.  The slab, however, will remain warm and keep your room at the desired temperature for several hours before requiring more hot water to circulate.

Two of the most popular radiant heat manifold systems, the Wirsbo TruFLOW system and the Mr. PEX radiant heat brass manifold, are detailed below.  Note that Wirsbo TruFLOW is the only system that accommodates 5/16” fittings to work with the 5/16” tubing used in QuickTrack Panels.

Purchasing the manifold and accessories
Supply & Return Adapters:  Both the TruFLOW and Mr. PEX units require that you purchase the supply and return thread adapters separately from the unit (TruFLOW- R32 thread, Mr. PEX- EK25 thread). These adapters are non- standard sizes, specific to the units.

TruFLOW Loop Connections: The R-20 threads required to make loop connections on the TruFLOW Manifold must be purchased separately from the manifold itself. Additionally, you have several choices for your loop fitting adapters:

· Compression style 1/2” QS-Style fittings do not require a tool and are the most common choice

· ProPex fittings allow you to put the tubing right onto the fittings without a thread. The expander tool is required for installation. (Copper pipe installation still requires a thread)

· Multicor fittings can only be used with Pex-al-Pex

Mr. PEX Loop Connections: The EK-20 loop threads and required fittings are included in the Mr. PEX Radiant Heat Brass Manifold Packages at PexSupply.com.  Note that Mr. PEX fittings are all unique sizes and cannot be used with the Wirsbo TruFLOW system

Suggestions for Installation
It is best to install the manifold and tubing at the same time. You should always pressure test your radiant system at the highest pressure before, during and after pouring the concrete to detect any leaks as early as possible. Both the TruFLOW and Mr. PEX systems require the pressure test kits made specifically for those units. A visual flow meter can also be purchased for this system to monitor it over time and to balance the system if there is any issue.

Oxygen barrier PEX-A tubing is the highest quality tubing and is recommended as the best option for a radiant heat system. It is the most flexible, has memory, and has the most options for fittings. It also expands in case the water in the system freezes. PEX-B and PEX-C also have oxygen barriers and are good for radiant heat systems, but are slightly harder to work with and can’t be used with the expansion tool.

Non-oxygen barrier PEX tubing is intended for plumbing. It should not be used for radiant heat except in the rare case that the system is being specially configured to run as an open loop system with your plumbing so that all the hot water going to your fixtures is also running through your floor. It is unsafe to use any cast iron or ferrous components with non-oxygen barrier tubing.

While aluminum PEX (PEX-al-PEX) can be used with radiant heat manifolds and multicar fittings, is not commonly run in slab because it is harder to work with and there is no standard tool. It is more common with the boiler installation. Despite common misconceptions about PEX-al-PEX, it does not necessarily have an oxygen barrier so be sure to select a type that does if you choose to use it for radiant heat.


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